• Proceedings of the Korean Society of Computer Information Conference
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• 2012.07a
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• pp.35-38
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• 2012

본 논문에서는 경추 초음파 DICOM 영상에서 심부 경부 굴곡근의 하단 후보 경계선을 이용하여 경추가 위치하는 후보 영역을 추출한다. 추출한 경추 후보 영역에 퍼지 시그마 이진화 기법을 적용하여 경추 객체를 추출한다. 심부 경부 굴곡근의 두께를 측정하기 위한 측정 기준점을 정확하게 추출하기 위해 심부 경부 굴곡근의 하단 경계선의 위치 정보를 이용하여 심부 경부 굴곡근내의 지방이 경추 객체로 추출되는 문제점을 개선하고, 개선된 영상에서 경추 객체들이 가진 픽셀 좌표를 이용하여 측정 기준점을 설정한다. 그 후, 객체들의 위치 정보를 이용하여 측정 기준점을 다시 설정한다. 심부 경부 굴곡근 영역과 측정 기준점을 이용하여 심부 경부 굴곡근의 두께를 측정한다. 제안된 방법을 경추 초음파 DICOM 영상에 적용하여 심부 경부 굴곡근의 두께를 측정한 결과, 기존의 심부 경부 굴곡근 두께 측정 방법보다 정확한 결과를 얻을 수 있는 것을 확인하였다.

• Composites Research
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• v.12 no.1
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• pp.59-67
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• 1999

The effects of fiber waviness on tensile/compressive nonlinear elastic behaviors of graphite/epoxy unidirectional composite materials are studied theoretically and experimentally. New constitutive models are proposed to predict elastic properties and tensile/compressive nonlinear behaviors of composite materials. Three types of wavy pattern are considered: uniform, graded and localized fiber waviness. Complementary energy density and incremental method are used to incorporate the material and geometrical nonlinearities due to fiber waviness. Tensile/compressive tests are conducted on the specimens with fiber waviness. It is found that the predictions are in good agreement with the experimental results.

• Journal of the Korea Institute of Building Construction
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• v.9 no.6
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• pp.169-174
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• 2009

We conducted structural analysis to investigate disadvantage of wire-mesh arranged at the plane and to develop three-dimensionally bent U-type wire-mesh. In all case that distributed loading at the whole top slab and the half top slab, and the wire mesh was bent $45^{\circ}$, flexura tensile stress was the fewest in both positive moment and negative moment, and the wire mesh was bent $45^{\circ}$ in crossway the shear stresss was the fewest. Therefore, by arranging wire-mesh with $45^{\circ}$ more bent than plane, flexura tensile stress, shear stress, displacement will be reduced and structural function will be improved.

• Journal of the Korean Society for Nondestructive Testing
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• v.21 no.3
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• pp.288-298
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• 2001

There has been a growing interest in thick composite materials especially for primary structures. Fiber waviness is one of the manufacturing defects frequently encountered in thick composite structures and affects the mechanical properties such as stiffness and strength significantly. Therefore, nondestructive evaluation technique that can detect fiber waviness of thick composite is very important for the integrity of structures. In this study, efforts were made to understand ultrasonic wave propagation in thick composites with uniform fiber waviness by adopting the ray and plane wave theories. Both theoretical and experimental investigations were conducted to understand the wave propagation in thick composites with uniform fiber waviness. The experiments were conducted on specially fabricated thick composite specimens with various degrees of uniform fiber waviness using the conventional through-transmission method to verify the predicted results. The experimental results showed good agreement with the theoretical predictions.

• Restorative Dentistry and Endodontics
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• v.31 no.1
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• pp.58-65
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• 2006

The possibility of applying a hi-axial flexure strength test on composite resin was examined using three point and hi-axial flexure strength tests to measure the strength of the light-cured resin and to compare the relative reliability using the Weibull modulus. The materials used in this study were light-curing restorative materials, $MICRONEW^{TM},\;RENEW^{(R)}$ (Bisco, Schaumburg, USA). The hi-axial flexure strength measurements used the piston-on-3-ball test according to the regulations of the International Organization for Standardization (ISO) 6872 and were divided into 6 groups, where the radius of the specimens were 12mm (radius connecting the 3-balls: 3.75mm), 16 mm(radius connecting the 3-balls: 5mm), and the thickness were 0.5mm, 1mm, 2mn for each radius. The hi-axial flexure strength of the $MICRONEW^{TM}\;and\;RENEW^{(R)}$ were higher than the three point flexure strength and the Weibull modulus value were also higher in all of the bi-axial flexure strength groups, indicating that the hi-axial strength test is relatively less affected by experimental error. In addition, the 2 mm thick specimens had the highest Weibull modulus values in the hi-axial flexure strength test, and the $MICRONEW^{TM}$ group showed no significant statistical difference (p>0.05). Besides the 2mm $MICRONEW^{TM}$ group, each group showed significant statistical differences (p<0.05) according to the thickness of the specimen and the radius connecting the 3-balls. The results indicate that for the 2mm group, the hi-axial flexure strength test is a more reliable testing method than the three point flexure strength test.

• Physical Therapy Korea
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• v.9 no.4
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• pp.45-52
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• 2002

이 연구의 목적은 수직착지시 성에 따른 슬관절 가동범위의 차이를 알아보는 것이다. 연구 대상자는 20대의 건강한 성인 48명(남자 25명, 여자 23명)이었다. 연구 대상자에게 40 cm 높이에서 한발로 뛰어내리도록 하고, 2차원 동작측정 기구인 CMS-HS를 이용하여 수직착지시 슬관절의 굴곡각도, 최대 슬관절 굴곡각도, 슬관절의 가동 범위, 각속도를 측정한 후, 남 여 두 집단간의 차이를 알아보았다. 이때 사용한 분석방법은 독립적인 두 표본 t-검정이었으며 축차적(stepwise) 다변량회귀분석을 이용하여 체중과 신장을 조절한 상태에서 남여 간에 차이가 있는지를 분석하였다. 그 결과 수직착지시 슬관절의 굴곡각도에서는 유의한 차이를 보이지 않았으나, 최대 슬관절 굴곡각도, 슬관절의 가동 범위, 각속도에는 유의한 차이가 있었다(p<.05). 체중과 신장이 조절된 조건 하에서 여자는 수직착지시 최대 슬관절의 굴곡각도와 슬관절의 가동범위가 남자보다 작았다. 이러한 결과를 통하여 수직착지시 여자가 남자보다 슬관절 손상의 빈도가 높은 이유 중의 하나는 여자가 슬관절을 덜 굴곡시킴으로 인해 바닥의 충격을 더 많이 받기 때문이라는 가능성을 발견하였다.

• The Journal of Korean Physical Therapy
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• v.12 no.2
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• pp.145-152
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• 2000

Pcak torque. angle of peak torque occurrence. total work, average power. endurance of the ankle plantar flexors were studied with the knee positioned $0^{\circ}\;and\;90^{\circ}$ flexion. Plantar flexors of 20 students were tested on Cybex 6000 dynamometer. The results were as fallows ; 1. The peak torque values were significantly higher with knee extension than knee $90^{\circ}$ flexion. 2. The angle of peak torque occurrence were earlier with knee extension than knee $90^{\circ}$ flexion, but no significant. 3. The total work were significantly higher with knee extension than knee $90^{\circ}$ flexion. at$30^{\circ}/sec$, but no significant at $90^{\circ}/sec$ 4. The endurance ratio were higher significantly with knee $90^{\circ}$ flex ion than knee extension 5. The mean average power were significantly higher with knee extension than knee $90^{\circ}$ flextion

• Proceedings of the Korean Information Science Society Conference
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• 2000.04b
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• pp.655-657
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• 2000

일반적으로 3차원 복셀 데이터의 가시화는 표면 복셀의 법선 벡터를 이용하여 퐁 반사 모형으로 밝기를 결정하는 일이라 할 수 있다. 표면의 변화가 부드러운 기하학적 모형의 가시화는 법선 벡터만으로 충분한 결과를 얻을 수 있지만, 표면의 굴곡이 심한 비정형의 데이터에는 적합하지 않을 수 있다. 따라서 본 논문에서는 물체 표면의 굴곡에 따라 빛의 양을 조절하여 이러한 문제를 개선하는 방법을 제안하였다. 이 방법으로 물체 표면의 굴곡을 고려하지 않을 때보다 물체가 선명하게 가시화되는 결과를 얻었다.

• Proceedings of the Optical Society of Korea Conference
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• 2003.02a
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• pp.288-289
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• 2003

피부 표면 굴곡의 측정은 피부의 광노화의 정량화 , 피부관련 약품 및 기능성 화장품의 효과 평가, 피부 질환 진단 등에 반드시 필요하다. 기존에 사용되던 측정법으로는 스타일러스 (Stylus)법, 그림자(Shadowing)법, Laser Profilometry법 등이 있으나 이 방법들은 해상도 및 속도, 가격 등에 있어서 일반적으로 사용되기에는 부적합하다. 본 연구에서는 이 단점들을 극복하고 더 나은 굴곡 측정을 위해서 높은 횡·종축 해상도를 얻을 수 있는 저 결맞음 간섭계 (Low Coherence Interferometry, LCI)를 이용하여 피부 표면의 굴곡을 측정하였다.(중략)

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.3
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• pp.183-195
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• 2020

Purpose: The purpose of this study is to compare the flexural strength of CAD/CAM denture base resins with conventional denture base resins based on their thicknesses. Materials and Methods: For the conventional denture base resins, Lucitone 199^® (C-LC) was used. DIOnavi - Denture (P-DO) and DENTCA Denture Base II (P-DC) were taken for the 3D printing denture base resins. For the prepolymerized PMMA resins, Vipi Block Gum (M-VP) and M-IVoBase^® CAD (M-IV) were used. The final dimensions of the specimens were 65.0 mm x 12.7 mm x 1.6 mm / 2.0 mm / 2.5 mm. The 3-point bend test was implemented to measure the flexural strength and flexural modulus. Microscopic evaluation of surface of fractured specimen was conducted by using a scanning electron microscope (SEM). After testing the normality of the data, one-way ANOVA was adopted to evaluate the differences among sample groups with a significance level of P = 0.05. The Tukey HSD test was performed for post hoc analysis. Results: Under the same thicknesses, there are significant differences in flexural strength between CAD/CAM denture base resins and conventional denture base resins except for P-DO and C-LC. M-VP showed higher flexural strength than conventional denture base resins, P-DC and M-IV displayed lower flexural strength than conventional denture base resins. Flexural modulus was highest in M-VP, followed by C-LC, P-DO, P-DC, M-IV, significant differences were found between all materials. In the comparison of flexural strength according to thickness, flexural strength of 2.5 mm was significantly higher than that of 1.6 mm in C-LC. Flexural strength of 2.5 mm and 2.0 mm was significantly higher than that of 1.6 mm in P-DC and M-VP. In M-IV, as the thickness increases, significant increase in flexural strength appeared. SEM analysis illustrates different fracture surfaces of the specimens. Conclusion: The flexural strength of different CAD/CAM denture base resins used in this study varied according to the composition and properties of each material. The flexural strength of CAD/CAM denture base resins was higher than the standard suggested by ISO 20795-1:2013 at a thickness of 1.6 mm or more though the thickness decreased. However, for clinical use of dentures with lower thickness, further researches should be done regarding other properties at lower thickness of denture base resins.